Synthesis of alkynyl, cyclic carbene and vinylidene osmium(II) complexes: first indenyl half-sandwich osmium(II) complexes

Abstract

The reaction of [OsCl(η5-C9H7)(PPh3)2]1 with 3,3-dimethylbut-1-yne and NaPF6 in refluxing methanol gave the vinylidene complex [Os{CC(H)But}(η5-C9H7)(PPh3)2][PF6]2a and with HCCSiMe3 and NH4PF6 in refluxing methanol gave the unsubstituted vinylidene complex [Os(CCH2)(η5-C9H7)(PPh3)2][PF6]2b. 2-Oxacyclo-pentylidene and -hexylidene complexes [Os{[graphic omitted]H2}(η5-C9H7)(PPh3)2][PF6](n= 1 3a or 2 3b) have been prepared by reaction of 1 with HCC(CH2)nCH2OH. Reaction of 1 and hex-5-yn-1-ol afforded the hydroxyvinylidene complex [Os{CC(H)(CH2)3CH2OH}(η5-C9H7)(PPh3)2][PF6]4 and with 1-ethynyl-1-cycloalkanols in the presence of NaPF6 in refluxing methanol it gave regioselectively the alkenylvinylidene complexes [Os{CC(H)[graphic omitted]H2}(η5-C9H7)(PPh3)2][PF6](n= 1 5a, 2 5b or 3 5c). Deprotonation of the vinylidene complexes 2a, 2b and 5a–5c with potassium tert-butoxide yielded the neutral alkynyl complexes [Os(CCR)(η5-C9H7)(PPh3)2](R = But6a or H 6b) and [Os{CC[graphic omitted]H2}(η5-C9H7)(PPh3)2]7a–7c respectively. Methylation of complex 6a with MeOSO2CF3 yielded the vinylidene complex [Os{CC(Me)But}(η5-C9H7)(PPh3)2][CF3SO3]8.